If we do not establish the means to ensure international cooperation, water could become a major source of conflict.

If water is set to dominate our 21st century world, then do we risk water wars? Many believe so. One vital necessity is a global reconciliation service, set up this year by UNESCO and the World Water Council. The Water Cooperation Facility is based at UNESCO in Paris. Its mission is to “promote cooperation, peace and prosperity in developing and managing transboundary waters.”

The task is potentially huge. Almost half the world’s population lives in international river basins. Two-thirds of these basins have no trea- › ties for sharing their water. The River Nile passes through ten countries. The Danube, Rhine, Niger and Congo all pass through nine, and the Zambezi through eight.

Africa – a continent of haphazard boundaries mostly created in the chaos of imperial rule – has 80 transboundary rivers. In Asia, Bangladesh and Pakistan receive more than 90% of their water from India. A meeting organised by UNESCO in Greece late last year heard how the fracturing of the former Yugoslavia has created seven new shared river basins.

Increasing numbers of countries also share underground water reserves. Jordan shares with Saudi Arabia the Disi aquifer that represents its “last substantial unexploited water resource”, according to a UN study. The vast Nubian basin aquifer straddles the borders between Libya, Egypt, Sudan and Chad.

Lack of knowledge about underground water resources is a major cause of tension. So UNESCO is currently undertaking a project to create the world’s most detailed map of Internationally Shared Aquifer Resources (ISARM). The African phase of the survey mapped 20 cross-border aquifers never delineated before. Ghanaians discovered they share an aquifer with Cote d’Ivoire. Benin learned that the aquifer providing water for the city of Cotonou extends across the border into Togo.

ISARM is helping these countries draw up rules for sharing the water. It has also serves as a meeting place where Israeli and Palestinian hydrologists share data about the much-disputed mountain aquifer that straddles the West Bank.

Half an Olympic-size swimming pool per person

Few of us realise how much water it takes to get us through the day. On average, we drink no more than five litres. Even after washing and flushing the toilet, we usually consume no more than 150 litres. But when we add in the water needed to grow what we eat and drink, the numbers soar.

It takes between 2,000 and 5,000 litres of water to grow one kilo of rice, over 1,000 litres for a kilo of wheat, between 2,000 and 11,000 litres to grow the feed for enough cow to make a quarter-pound hamburger, and between 2,000 and 4,000 litres for that cow to fill its udders with a litre of milk.

Every teaspoonful of sugar requires 50 cups of water, and every cup of coffee 140 litres. Hoekstra calculates that his fellow Netherlanders require the virtual-water equivalent of 4% of the flow of the Rhine to produce the coffee they drink in a year. To feed and clothe a typical meat-eating Westerner for a year takes around 1,500 cubic metres – rather more than half the contents of an Olympic-size swimming pool.